Clients never need to sign up for an account themselves! Here is the fix if a client signs up for a trainer account.
Trainer codes are the key to changing an accidental trainer account signup to a client account. The client must receive the trainer code from the desired trainer they intend to work with.
If you are their trainer, read here for how to find your trainer code on any platform: https://www.fitsw.com/help/?s=trainer+code&ht-kb-search=1&lang=
When the client is logged in (as an incorrect trainer account), navigate to the account settings page from the dashboard by clicking the icon in the top right corner of the screen.
Then, scroll down all the way to the bottom of the page until you find the section named Account Type.
Check the box next to the words, “Change account to a client account.” It will prompt you to enter your trainers code which you should have obtained from your desired trainer. After entering the code, press the blue Change to Client button and now you are all set!